It highlighted how many of the computers controlling infrastructure in the US - like dams, bridged and power systems - are old and vulnerable.

Robert M Lee, a former US air force cyberwarfare expert, said: "If the geopolitical situation changes and Iran wants to target these facilities, if they have this kind of information, it will make it a lot easier."

Nearly 300 hacking incidents at infrastructure sites in the US were reported to the department of homeland security in the last year. Intelligence analysts who discovered the attack on the Bowman Avenue Dam initially believed, mistakenly, that hackers were targeting a much larger structure, the Arthur R Bowman Dam in Oregon, which is 245ft tall, and they alerted the White House.

A spokesman for the the department of homeland security said: "We continue to coordinate national efforts to strengthen the security and resilience of critical infrastructure."